Blown plastic containers with threads

ABSTRACT

A blown plastic container that includes a hollow plastic body, an integral blow-molded neck and an integral blow-molded finish with a radially outwardly extending blow-molded thread or bead for retaining a closure on the finish. Reinforcement is provided between the thread or bead and a ledge on the finish to prevent collapse of the finish when a closure is applied to the finish. In one form, this reinforcement includes blow-molded axial columns extending radially outwardly. In another form, the reinforcement includes geometric depressions. The reinforcement preferably is disposed circumferentially at equal angular spacing. When the container is trimmed, the finish may have an annular frustoconical radial ledge spaced from the open end of the finish. The reinforcement extends between the ledge and the lowest thread or bead, between the thread or bead, or for the full height of the finish above the ledge.

This is a division of application Ser. No. 08/948,923 filed Oct. 10,1997 now U.S. Pat. No. 6,105,800.

This invention relates to blown plastic containers and particularly toblown plastic containers that include a finish which has threads formedthereon.

BACKGROUND AND SUMMARY OF THE INVENTION

In blown plastic containers made by an extrusion blow molding process,it is common to form retention means on the finish by blow molding. Suchretention means may comprise threads on the finish for engagement withthreads on a closure. Where the retention means comprises a blow moldedbead on the container, the compressive axial force of application of aclosure by closure application machinery can collapse the finish. Thismay also occur where a container is made into a plastic tube by cuttingoff the base of the container after application of the closure. Theaxial force of application of the force coupled with the flexibility ofthe side wall of the container may result in inadequate retention of theclosure. As a result, the desired off torque force is not maintained. Ithas been found that where the finish includes blown threads, when aclosure is applied by closure application machinery, the controlledapplied torque force collapses the finish and strips the closure off thefinish. This occurs where the selected container finish and closure maynot be fully compatible, that is, the threads and closures areimperfectly matched.

Among the objectives of the present invention are to provide a blownplastic container where the finish is sufficiently strong that it willnot collapse when a closure is torqued or pressed onto a filled orunfilled container; where the closure will not readily strip off whenbeing applied and the desired off torque will be maintained; and toprovide a method of forming the finish to achieve such a result.

In accordance with the invention, the blown plastic container includes ahollow plastic body, an integral blow molded neck and an integral blowmolded finish with a radially outwardly extending blow molded retentionmeans such as thread or bead on the finish. In one form, the reinforcingmeans comprises blow molded axial columns extending radially outwardly.In another form, the reinforcing means comprises geometric depressions.Preferably, the reinforcing means are disposed circumferentially atequal spacing. When the extrusion blow molded container is trimmed, thefinish may have an annular frustoconical radial ledge spaced from theopen end of the finish. The projection means may extend between theledge and the lowest mold threads or beads; between the threads or beadsor for the full height of the finish above the ledge.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of an extrusion blow molded containerembodying the invention.

FIG. 2 is a fragmentary enlarged elevational view of the finish on thecontainer shown in FIG. 1.

FIG. 3 is a top plan view of the finish shown in FIG. 2.

FIG. 4 is a sectional view taken along the line 4—4 in FIG. 3.

FIG. 5 is a sectional view on an enlarged scale taken along the line 5—5in FIG. 3.

FIG. 6 is a sectional view taken along the line 6—6 in FIG. 2.

FIG. 7 is a fragmentary perspective view of the finish.

FIG. 8 is a fragmentary perspective view of a modified form of finish.

FIG. 9 is a fragmentary enlarged elevational view of another modifiedform of a finish of a blown container embodying the invention.

FIG. 10 is a top plan view of the finish shown in FIG. 9.

FIG. 11 is a sectional view taken along the line 11—11 in FIG. 10.

FIG. 12 is a sectional view taken along the line 12—12 in FIG. 10.

FIG. 13 is a sectional view taken along the line 13—13 in FIG. 9.

FIG. 14 is a sectional view taken along the line 14—14 in FIG. 9

FIG. 15 is a sectional view taken along the line 15—15 in FIG. 9

FIG. 16 is a fragmentary enlarged elevational view of another modifiedform of finish of a container embodying the invention.

FIG. 17 is a top plan view of the finish shown in FIG. 16.

FIG. 18 is a sectional view taken along the line 18—18 in FIG. 17.

FIG. 19 is a sectional view taken along the line 19—19 in FIG. 17.

FIG. 20 is a sectional view taken along the line 20—20 in FIG. 16.

FIG. 21 is a sectional view taken along the line 21—21 in FIG. 16.

FIG. 22 is a sectional view taken along the line 22—22 in FIG. 16.

FIG. 23 is a fragmentary elevational view of another modified form offinish of a container embodying the invention.

FIG. 24 is a top plan view of the finish shown in FIG. 23.

FIG. 25 is a sectional view taken along the line 25—25 in FIG. 24.

FIG. 26 is a sectional view taken along the line 26—26 in FIG. 24.

FIG. 27 is a sectional view taken along the line 27—27 in FIG. 23.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, in accordance with the invention, a blow moldedplastic container 30 is made by extrusion blow molding wherein a parisonis extruded, blow molds closed about the parison and the parison isblown to the confines of the cavity of a mold to form a blow moldedcontainer and a blow molded finish. The container 30 includes a hollowplastic body 32, an integral blow molded shoulder 34 and an integralblow molded finish 36 with a radially outwardly extending thread 38 onthe finish 36. The thread 38 may be a single threaded or a multiplethread herein shown as a double thread. The thread preferably includesan extra quarter turn as shown in FIG. 7 but the thread 38 a can be an180 degree thread as shown in FIG. 8. The container also preferablyincludes an integral blow molded ledge 40 and an integral blow moldedhandling bead 42. However, the ledge 40 and handling bead 42 may beomitted.

In accordance with the invention, the finish 36 has integrally blowmolded reinforcing means thereon. In the form shown, the reinforcingmeans comprises blow molded axial columns 44 which extend radiallyoutwardly between the lowermost portion of threads 38 and ledge 40 (FIG.2). Preferably, the columns 44 are disposed circumferentially at equalspacing as shown in FIG. 3. As shown in FIGS. 3-5, finish 38, includingcolumns 44, is of generally uniform radial wall thickness.

In the modified form of the invention shown in FIGS. 9-15, thereinforcing means comprises axially extending blow molded columns 44, 44a between the threads and columns 44 b between the top thread portionand an annular rib 50 which extends radially outwardly.

In the modified form of the invention shown in FIGS. 16-22, thereinforcing means comprises blow molded means 52 comprise blow moldedcircular indentations but may comprise any geometric shape which providestructural strength such as squares, rectangles, rounds, ovals,triangles, diagonal ribs herein shown having a curves cross section.

In the modified form shown in FIGS. 23-27, the blow molded reinforcingmeans 54 comprise columns which extend between retention means in theform of a blow molded retention bead 56 and the shoulder 58 of thecontainer.

It can thus be seen that there has been provided a blown plasticcontainer where the finish is sufficiently strong that it will notcollapse when a closure is torqued or pressed onto a filled or unfilledcontainer. The closure will not readily strip off when being applied andthe desired off torque will be maintained; and to provide a method offorming the finish to achieve such a result.

I claim:
 1. A method of manufacturing a hollow plastic container that comprises the steps of: (a) extruding a tubular parison, (b) closing blow molds around the parison, and (c) blow molding the parison to form an integrally molded container having: a blow molded hollow plastic container body, a container finish with retention means extending circumferentially around the finish for retaining a closure on said finish, said finish, including said retention means, being of generally uniform radial wall thickness, a circumferentially extending radially outwardly projecting ledge axially spaced from said retention means, and reinforcing means, also of said generally uniform radial wall thickness, extending axially from said retention means to said ledge, and circumferentially around said finish between said retention means and said ledge so as to impart a continuous undulating cross section to said finish in a plane lateral to said finish between said retention means and said ledge for strengthening the container finish against collapse as a closure is applied to said finish.
 2. The method set forth in claim 1 wherein said reinforcing means comprise depressions.
 3. The method set forth in claim 2 wherein said retention means comprise thread means and said blow molded depressions extend between said thread means.
 4. The method set forth in claim 2 wherein retention means comprises blow molded multiple threads and said blow molded depressions extend between said multiple threads.
 5. The method set forth in claim 1 wherein said retention means comprise a retention bead.
 6. The method set forth in claim 5 wherein said reinforcing means comprises blow molded geometric portions on said finish.
 7. The method set forth in claim 6 wherein said retention means comprises thread means.
 8. The method set forth in claim 7 wherein said reinforcing means comprises integral blow molded axial columns extending radially outwardly.
 9. The method set forth in claim 8 wherein said columns extend between said thread means.
 10. The method set forth in claim 8 wherein said thread means comprises a single thread having overlapped ends and said columns extend between thread portions.
 11. The method set forth in claim 8 wherein said thread means comprises multiple threads and said columns extend between said multiple threads means.
 12. The method set forth in claim 1 wherein said step of blow molding said parison forms an integral blow molded portion extending from said finish, and further includes the step of trimming said integral hollow portion from said finish.
 13. A method of making a hollow plastic container finish that comprises the steps of: (a) extruding a tubular parison, (b) closing blow molds around the parison, and (c) blow molding the parison to form an integrally molded container finish having: retention means extending circumferentially around the finish for retaining a closure on said finish, said finish, including said retention means, being of generally uniform radial wall thickness, a circumferentially extending radially outwardly projecting ledge axially spaced from said retention means, and reinforcing means, also of said generally uniform radial wall thickness, extending axially from said retention means to said ledge, and circumferentially around said finish between said retention means and said ledge so as to impart a continuous undulating cross section to said finish in a plane lateral to said finish between said retention means and said ledge for strengthening the container finish against collapse as a closure is applied to said finish.
 14. The method set forth in claim 13 wherein said reinforcing means has a lesser radial dimension than said retention means so as not to interfere with application of a closure to said retention means.
 15. The method set forth in claim 13 wherein said retention means comprises at least one thread.
 16. The method set forth in claim 15 wherein said at least one thread comprises a single thread extending more than 360 degrees around said finish and said reinforcing means extend between overlapped ends of said single thread.
 17. The method set forth in claim 16 wherein said at least one thread comprising multiple threads and said reinforcing means extend between said multiple threads.
 18. The method set forth in claim 13 wherein said reinforcing means comprises integral molded axial columns extending radially outwardly and axially along said finish.
 19. The method set forth in claim 13 wherein said reinforcing means comprises molded geometric portions on said finish.
 20. The method set forth in claim 13 wherein said reinforcing means comprises depressions.
 21. The method set forth in claim 13 wherein said retention means comprises a retention bead.
 22. The method set forth in claim 13 where said finish is blow molded with a hollow body forming a one-piece container. 